“Track and Trace” systems are currently used in different fields of industry. Many industries suffer from counterfeit or diverted products, in particular in the field of mass-produced items such as beverages, perfumes, pharmaceutical drugs, cigarettes, CDs/DVDs, as well as other kind of consumables. Counterfeiting and market diversion are facilitated if the mass products are handled on a lot base, rather than on an individual item base. Counterfeit or diverted products are in such case easily introduced into the supply chain. Producers and retailers would like to be in a position to distinguish their original products from such counterfeit or diverted (parallel imported) products at the level of the individual unit which can be sold.
The underlying technical problem has been addressed in the art through an individual marking of each sellable item introduced into the supply chain. The markings of the prior art were chosen in such a way that they were not susceptible to photocopying, i.e. preferably covert markings were used, which are not visible to the unaided eye or the photocopying machine.
A “Covert” marking, in the context of the present invention, is any marking or security element, which cannot be authenticated by the unaided eye, but which, for authentication, depends on a detecting or reading device of any kind, such as an optical filter or an electronic authentication equipment.
An “Overt” marking, in the context of the present invention, is any marking or security element, which, for authentication, does not depend on a detecting or reading device; i.e. which can be authenticated by the unaided eye.
“Color” in the context of the present invention is used to designate any spectrally selective return of light (electromagnetic radiation) from an illuminated object, be it in the visible, the infrared or in the UV range of the electromagnetic spectrum (i.e. in the whole wavelength range from 200 nm to 2500 nm).
The term “visible” is used to indicate that a property can be revealed by the unaided eye; “detectable” is used for a property that can be revealed by an optical instrument, though not necessarily by the unaided eye, and “invisible” is used for a property that cannot be detected by the unaided eye. In particular, the term “visible color” means a spectrally selective return of light in the wavelength range from 400 nm to 700 nm, which is detectable by the unaided eye.
In the context of the present invention, the terms material and composition are interchangeable.
A first type of individual markings, useful to prevent counterfeit and diversion, is disclosed in U.S. Pat. Nos. 5,569,317, 5,502,304, 5,542,971 and U.S. Pat. No. 5,525,798. According to these documents, a bar code is applied onto the item, using an ink which is not detectable under light of the visible spectrum (400-700 nm wavelength) but which becomes visible when illuminated with light of the UV spectrum (200-380 nm wavelength).
A second type of individual markings is disclosed in U.S. Pat. Nos. 5,611,958 and 5,766,324. According to these documents, a marking is applied onto a commercial good, using an ink which is not detectable in the visible spectrum, but which can be detected through illumination with light of the infrared spectrum (800-1600 nm wavelength).
Yet another type of individual markings, applied through an ink, is disclosed in U.S. Pat. Nos. 5,360,628 and 6,612,494. This marking needs to be illuminated jointly with UV- and IR-light to be revealed.
Still another type of individual marking relies on inks comprising up-converting phosphors such as described in U.S. Pat. No. 5,698,397.
All of the markings mentioned in the cited prior art are covert markings, which are completely invisible to the unaided human eye. The reading of such covert markings depends on a corresponding detecting or reading device, able to detect or read the marking. This can be a disadvantage at the retail center or at the point-of-sale, where an appropriate reading device may not always be available.
Overt markings comprising “optically variable” features, e.g. exhibiting viewing-angle dependent color, have been proposed in the art as authentication means for the “person in the street”. Among these are the holograms (cf. Rudolf L. van Renesse, “Optical Document Security” 2nd ed., 1998, chapter 10), the optical thin film security devices (idem, chapter 13) and the liquid crystal security devices (idem, chapter 14).
Particularly useful as security devices are the cholesteric liquid crystals. When illuminated with white light, the cholesteric liquid crystal structure reflects light of a determined color, which depends on the material in question and generally varies with the angle of observation and the device temperature. The cholesteric material itself is colorless and the observed color is only due to a physical reflection effect at the cholesteric helical structure adopted at a given temperature by the liquid crystal material. (cf. J. L. Fergason, Molecular Crystals, Vol. 1, pp. 293-307 (1966)). In particular liquid crystal materials, the cholesteric liquid crystal polymers (CLCPs), the cholesteric helical structure is “frozen” in a determined state through polymerization, and thus rendered temperature-independent.
If the cholesteric liquid crystal material is applied on a dark or black background, its reflection color is highly apparent to the unaided eye, because the light transmitted by the cholesteric material is largely absorbed by the background, so that the residual backscattering from the background does not disturb the perception of the cholesteric material's own reflection. A careful choice of the background color can thus contribute to the visibility of such an overt marking.
On a clear or white background the reflection color of the cholesteric liquid crystal material is virtually invisible due to the superposition of the cholesteric material's own reflection with the strong backscattering from the background. The cholesteric liquid crystal material can, however, always be identified with the help of a circular polarization filter because it selectively reflects only one of the two possible circular polarized light components, in accordance with its chiral helical structure.
EP-B1-1 381 520 and EP-A1-1 681 586 refer to a birefringent marking and a method of applying the same in the form of a liquid crystal layer having a non-uniform pattern of regions of different thickness. The applied liquid crystal coating or layer may provide for a hidden image on a reflective substrate, which is invisible when viewed under unpolarized light but rendered visible under polarized light or with the help of a polarization filter.
U.S. Pat. No. 5,678,863 refers to means for the identification of documents of value which include a paper or polymer region, said region having a transparent and translucent characteristic. A liquid crystal material is applied to the region to produce an optical effect, which differs when viewed in transmitted and reflected light. The liquid crystal material is in liquid form at room temperature and must be enclosed in a containing means such as microcapsules, in order to be used in a printing process such as gravure, roller, spray or ink-jet printing. The printed liquid crystal region can be in the form of a pattern, for example a bar code. The pattern can be verified by visual or machine inspection of the polarization states of the areas having left-handed and right-handed liquid crystal forms.
U.S. Pat. No. 5,798,147 refers to coating compositions of polymerizable liquid crystal monomers which can be applied by conventional printing processes, such as letterpress, rotogravure, flexographic, offset, screen, and ink-jet printing. The printing inks can be used to produce markings and security inscriptions which are invisible to the human eye. The markings can be detected by their circular polarization or their angle dependent reflection color.
U.S. Pat. No. 6,899,824 refers to a process for printing or coating a substrate with a multilayer of a liquid-crystalline composition and at least one non-liquid-crystalline coating. The process and the printed substrate are useful for producing a counterfeit-proof marking of articles. Preferred methods for applying such printing or coating are screen printing, planographic printing, flexograhic, and letterpress printing.
None of the markings disclosed in the prior art does, however, provide a solution to the technical problem underlying “track & trace” applications, wherein, in addition to a machine-readable individual coding of items with a counterfeit-resistant security marking, an easy authentication of the marking by the unaided eye is required.
“Track & Trace” applications are known in the art for e.g., postal services, wherein each mail piece is individually marked and followed throughout its delivery chain. Barcodes, such as 1D-barcodes, stacked 1D-barcodes, 2D-barcodes or matrix-codes, are most often used as the marking and identification means.
No particular effort is devoted to authentication aspects in the case of the said postal markings, given that the mail piece is handled service-internally by the mailing company throughout the entire delivery chain, so that no authentication is needed. Postal “Track & Trace” applications are merely focused on the identification of the mail piece.
Authentication aspects are, however, of crucial importance in retail applications, where there is a potential risk of substitution of the original goods by counterfeit or diverted ones. For this reason, “Track & Trace” applications in this field must be combined with at least one security element, able to certify the authenticity of the marked good as an original one.
In the following, “Secure Track & Trace” means the combination of a “Track & Trace” application, which allows for the identification of an individual item, with at least one security element, which additionally allows for the authentication of the said item as being genuine.